I would go with the JBJ systems. They are a lot better now, the bugs have been worked out mostly. You can get little skimmers that sit on down in the filter part as well, and other than that there is nothing else to buy. They are the least expensive route for a decent size, decent lights, and decent filter system and it is all built in.
If you have bit more money to spend, look at the M-tanks. They are really nice, if you can find them in stock anywhere. You can get them with MH lights, and the built in trickle filter is wild.
If you are DIY on this, I would just be real careful. My little experiment worked out fine, but with a tank this size, it does not take much to royally mess it up. One simple thing like temp in the corner of the room where the tank is can do it, but that goes for all of them.
The one thing about nano tanks is that there is no 'wrong' way to do one, this part of the hobby is wide open to experiments and change. Whatever works for you is 'right'.
Fish can be really good for a system with corals in it. Think fertilizer and more random water flow. Plus keeping pod population in check, there are more ups than downs with a very small fish. 5 gallon, I would think a neon goby or two. Just some flash for the tank.